Autoimmune epilepsy and/or limbic encephalitis can lead to changes in sleep spindles

Introduction: Sleep disorders have been described in patients with autoimmune limbic encephalitis (LE). The changes in sleep structure were also reported. Recently sleep spindle abnormalities such as asynchronous or prolonged spindles were observed children with LE. Methods: We studied the sleep and number of sleep spindles in the continuous electroencephalography-polysomnography (EEG-PSG) recordings of 6 patients with autoimmune epilepsy and/or LE. The longest NREM 2 period was selected. We evaluated the spindle density (spindles per minute), and compared that to the spindle densities of epilepsy patients with bilateral hippocampal sclerosis and healthy controls. Results: We have demonstrated that patients with autoimmune epilepsy and/or LE had reduced slow wave sleep with decreased number of sleep spindles. The mean number of spindles in 60 seconds was 5.86±5.03 in patients with autoimmune epilepsy and/or LE. But spindle density was higher in two control groups (10.6±1.65 and 9.95±0.79). Conclusions: The sleep abnormalities in LE can result from the disruption of thalamo-limbic circuits, and lead to changes in spindle wave activity. Although density of spindles decreased with acute lesions in thalamo-limbic circuits, the relations with structural lesions or chronicity of disease are not clear. That may be related to functional disruption of neural circuitry.